12

TECHNICAL SPECIFICATIONS FOR 33/11kV POWER

TRANSFORMER

1.0 SCOPE OF SPECIFICATION:

1.1. : This specification is intended to cover design, manufacture, assembly testing at

manufacturer‟s works, supply and delivery of three phase 50HZ, 33/11 KV

Delta/Star, Vector Group DY 11, two windings copper would outdoor type, oil

immersed, naturally air cooled Power Transformer with off load tap changer for

10MVA , 5 and 2.5MVA transformer.

1.2. The transformer offered shall be complete with all parts and accessories which are

necessary for their efficient and satisfactory operation The Transformer and all

associated oil filled Equipment shall be supplied complete with insulating new oil

required for first filling including 10% extra oil for future use during commissioning.

The Transformer tank shall be dispatched completely filled with oil and the balance

oil shall be supplied in non returnable sealed drums along with the Transformers.

1.3. Such parts and accessories shall be deemed to be within the scope of this

specification whether specifically mentioned or not. Main tank body may be delivered

in unpacked condition, but delicate parts like indicating meter, radiator, conservator,

Pressure Relief Valve, equalizer pipe, buchholz relay etc. shall be packed to avoid

damage due to transportation.

1.4. It may be noted that the Power Transformer must meet the following minimum

criteria. Failure to comply with the requirements may results in rejection of the BID

as non-responsive:

1.5. The Manufacturer must have designed, manufactured, type tested and supplied

power transformers in at least two power utilities of similar rating which are in

successful operation for at least 5 (Five) years as on the date of bid opening. Which

should be substantiated by furnishing performance report by the official of the rank

of minimum DGM/SE

1.6. The Manufacturer should have in-house Auto Clave facility

1.7. Impulse Test, Temperature Rise and Loss Measurement shall be carried out at

CPRI / NABL accredited Laboratory.

.

2.0 : ISOCERAUNIC CONDITION:

For the purpose of designing, the following condition shall be considered:

1. Maximum temperature of air in shade 40°C

2. Minimum temperature of air in shade 2°C

3. Maximum temperature of air in sun 45°C

4. Maximum humidity 100%

5. Average number of thunder storm days per 45 Days

annum 6. Maximum rainfall per annum 3500 mm

7. Average rainfall per annum 2200 mm

8. Wind pressure 97.8 Kg/m2

9. Altitude above MSL 100 to 1000 M

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3.0 APPLICABLE STANDARDS

Unless otherwise stated, transformer shall be designed, constructed and tested in

accordance with provisions contained in latest revisions of following Indian

standards and Rules.

i. IS : 2026

ii. R.E.C. Manual 10/1976

iii. C.B. I.P. Manual on Transformer

iv. Technical Report 1: Section : A.D. (Revised: 1987)

v. C.B.I.P. Technical Report No. 72 (June: 1989)

vi. Indian Electricity Rules, 1956 (Amended up to date)

vii. IS : 2099 Bushing for alternating voltage above 1000 volt

viii. IS: 6600 Guide for loading of oil immersed transformer

ix. Specification for Transformer oil (IS-335 & IS-1866,1983)

x. Other applicable Indian Standards, or equivalent international specifications

4.0 GUARANTEES

The bidder shall guarantee among other things the following:

a) Quality and strength of the material used.

b) Adequate factors of safety for all parts of equipment to withstand the mechanical and on electrical stresses developed therein. These will be stated in the tender.

c) Suitability of the design and workmanship of the equipment for the conditions envisaged in the specification.

d) Efficiencies, Temperature rise and other performance data on equipment which shall be furnished in the tender.

5.0 WARRANTY

5.1. The bidder shall be responsible for replacing at site free of cost any part or parts of

the equipment that may prove faulty or fail manufacturing defects on one or more of

the reasons given in clause stated above within 60 (sixty) months from the date of

commissioning or 66(sixty six) months from the date of receipt of the

materials at our store in good and acceptable condition whichever is earlier

5.2. In case of failure of the transformer, the supplier shall take back the faulty

transformer from its plinth for repair at their own cost (or replace the transformer with

a new transformer) and deliver, at their own cost, unload at the destination sub-

station transformer plinth within 45 days, from the date of intimation of defects to the

satisfaction of the owner, at free of cost. If the repair/replacement will not be

completed within 45 days, then the supplier shall pay penalty @ 0.5% of the contract

price for each calendar week of delay from the end of 45 days from the date of

intimation of defects. Also, the Purchaser reserves the right for forfeiture of the total

Composite Bank Guarantee and all the Securities, available with APDCL, in case the

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Supplier fails to pay the penalty by one month before the expiry of the guarantee

period. Also, this will be taken as adverse in all future tenders.

5.3. The bidder shall furnish copies of test certificates of materials used for manufacture

and also the test certificates of the tests conducted on the equipment after

manufacture. The contractor shall also furnish the test certificate of bought out

components for approval by the purchaser.

6.0 MISCELLANEOUS

6.1. Padlocks along with duplicate keys as asked for various valves, marshalling box etc.

shall be supplied by the contractor, wherever applicable.

6.2. Foundation bolt for wheel locking devices of Transformer shall be supplied by the

bidder.

7.0 DELIVERY SCHEDULE:

The equipment shall be delivered FOR Destination as per schedule specified in the

BPS

8.0 CONFLICT IN CLAUSE:

In case of any conflict between the Specific Technical Requirements and General

Technical Requirements the requirements indicated as Specific Technical

Requirement shall prevail over the General Technical Requirements

9.0 DEVIATION FROM SPECIFICATION

9.1. Normally the offer should be as per Technical Specification without any deviation.

But any deviation felt necessary to improve utility, performance and efficiency of

equipment or to secure overall economy shall be mentioned in the „Schedule of

deviations” with full justification, supported by documentary evidence. Such

deviations, suggested, may or may not be accepted. But deviations, not mentioned

in the “Deviation Schedule” will not be considered.

10.0 DRAWINGS INCORPORATING THE FOLLOWING PARTICULARS SHALL BE

SUBMITTED WITH THE BID:

10.1. The following drawings and details shall be furnished in triplicate along with the bid :

10.2. General Arrangement outline drawing with plan, elevation and end views showing

various dimensions of transformer and its vital component including height of the

bottom most portion of bushing from the bottom of base channel and also indicating

thereon physical centre line and position of centre of gravity.

10.3. Details of various types of bushing.

10.4. Three copies of sketches for height of crane hook above ground for lifting and

untanking core, shipping dimensions, complete lists of fittings and devices, net

weights of core, winding, tank, radiator, oil, conservator and total weight, fixing

arrangement of transformer in foundation.

10.5. Illustrative & descriptive literature of the Transformer.

10.6. Maintenance and operation Instructions.

10.7. Type test certificates of similar transformers.

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11.0 RATING AND GENERAL PARTICULARS:

11.1. Type: Core type, three phase, oil immersed, step down, two winding copper wound

transformer for outdoor installation.

11.2. Standard Rating:

Continuous with off circuit taps as mentioned in the schedule of requirement.

11.3. Continuous Maximum Rating and Overloads:

As regards maximum rating and temperature rise, all transformers shall comply with the appropriate requirement of Indian Standards For the purpose of consideration of maximum temperature rise of oil and winding, the following ambient temperatures are assumed.

i. Cooling medium : Air

ii. Maximum Ambient Air temperature: 50 °C.

iii. Maximum daily average ambient Air temperature: 40 °C.

iv. Maximum yearly weighted average temperature: 32 °C .

11.4. The transformer may be operated without danger on any particular tapping at the

rated KVA provided the voltage does not vary by more than +10% of the voltage at

that tapping.

11.5. The transformer should be suitable for continuous operation with a frequency

variation of +3% from normal 50Hz. Combined voltage and frequency variation

should not exceed the rated V/f ratio by 10%

11.6. DUTY UNDER FAUALT CONDITION

11.7. It is to be assumed that normal voltage will be maintained on one side of the

Transformer when there is a short circuit between phases or to earth on the other

side.

11.8. The transformer may be directly connected to an underground or overhead line and

may be switched into and out of service together with or without its associated

incoming/outgoing line.

11.9. The thermal ability to withstand short circuit shall be Two seconds (2 Sec.) without

injury for 3 phase dead short circuit at the terminals.

12.0 GENERAL TECHNICAL PARAMETERS

SN Particulars

1. Rating 5MVA

2. Number of Phases Three

3. Vector group Dyn-11

4. Type of installation Outdoor

5. Frequency 50HZ ( +/- )3%

6. Cooling Medium Insulating Oil

7. Type of Cooling ONAN

8. Highest continuous system Voltage

High Voltage :36kV

Low Voltage :12kV

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9. Winding Connection

10. Material Electrolytic Copper

11. High Voltage Winding DELTA

12. Low Voltage Winding STAR

13. Method of System Earthing Solidly grounded on LV side

5 MVA

14. Type of Tap Changer OFF Load

15. Range of Tapping (+) 3% to (-) 9% in steps of 3% on HV side

16. Type of Insulation and Insulation Level 33kV 11kV

17. a) Type of insulation Uniform Uniform

b) One minute power frequency

withstand Voltage(kV rms)

70kV 28kV

c) Lightning Impulse withstand

voltage

170 75

18. Terminal Details

19. 33kV Termination (i) ACSR/AAAC Wolf conductor, Bus, (or IPs tube as applicable) for connecting to bushing terminals.

20. 11 KV Termination Cable 300/630 mm2, 1-core Al.

Armoured XLPE Cable

21. Maximum Temperature rise over ambient of 50° C

a) Temperature rise of top oil

40° C (measured by Thermometer

b) Temperature rise of winding 45° C (measured by resistance)

C) Maximum Winding temperature in Deg. C

105° C

d) Maximum Permissible value

of Average temperature of winding

after 3 sec Maximum Permissible

short circuit:

250° C

12.1. Over load capacity As per IS: 6600 or equivalent international specifications

12.2. NOISE LEVEL AT RATED VOLTAGE & FREQUENCY: As per NEMA

Pub TR-1.

13.0 GUARANTEED LOSSES

1. Impedance at rated MVA at 75° C without (-) ve tolerance

7.15%

2. No Load Loss (at rated voltage and rated current)

4.0KW

3. Load Loss at 75° C (at rated voltage and rated current)

24KW

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Tolerance of losses shall be guided by the relevant clauses of relevant IS standard.

The bidder shall state both no load loss and load loss at rated voltage and frequency

and loss figures shall be firm and guaranteed.

14.0 Evaluation of Losses:

14.1. For the purpose of comparison of bids, the capitalized cost of iron loss (KW) and

load losses (KW) shall be added to the quoted price of transformer at the

following rates.

3.1.1 Iron loss per KW – ₹. 287 834.00

3.1.2 Copper loss per KW – ₹. 86349.00

14.2. If any or all actual losses after test are found to exceed the guaranteed value, the

penalty will be imposed on the excess loss over the corresponding guaranteed

loss (any or all). The penalty shall be calculated for the excess of no load loss

and for the excess of the load losses at rates specified above. For fraction of a

KW the penalty shall be applied prorate basis. If the test figure of. losses are less

than the guaranteed value, no bonus will be allowed. Any changes in the figure

assigned for transformer losses will not be permitted after opening of bids and bid

evaluation will be carried out on the basis of information made available at the

time of bid opening.

15.0 SHORT CIRCUIT CALCULATIONS

15.1. Manufacturer shall submit theoretical calculations in support of the ability to

withstand short circuit on consideration of highest value that may

16.0 PERFORMANCE CERTIFICATES

16.1. Copies of performance certificates of sImilar Equipment supplied to various

utilities shall have to be furnished along with Tender

17.0 LIST OF PAST SUPPLIES

17.1. The bidder shall furnish documents in support of Supply, Delivery of similar

Equipment indicating thereon names of the organization, quantity ordered,

quantity supplied along with tender.

18.0 DESIGN, STANDARDIZATION AND GENERAL CONSTRUCTION FEATURES

18.1. .All material used shall be best quality and of the class most suitable for working

under the conditions specified and shall withstand the variations of temperature

and atmospheric conditions without distortion or deterioration or the setting up of

undue stresses which may impair suitability of the various parts for the work

which they have to perform.

18.2. Large parts, particularly removable ones, shall be interchangeable. Pipes and

pipe fittings, screws, studs, nuts and bolts used for external connections shall be

as per the relevant standards. Steel bolts and nuts exposed to atmosphere shall

be of hot deep galvanized

18.3. Nuts, bolts and pins used inside the transformers and tap changer compartments

shall be provided with lock washers or locknuts. Exposed parts shall not have

pockets where water can collect.

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18.4. Internal design of transformer shall ensure that air is not trapped in any location.

Material in contact with oil shall be such as not to contribute to the formation of

acid in oil. Surface in contact with oil shall not be galvanized or cadmium plated.

18.5. Labels, indelibly marked shall be provided for all identifiable accessories like

relays, switches, current transformers etc. All label plates shall be of in corrodible

material.

18.6. All internal connections and fastening shall be capable of operating under

overloads and over-excitation, allowed as per specified standard without injury.

18.7. Transformers and accessories shall be designed to facilitate proper operation,

inspection, maintenance and repairs. No patching, plugging, shimming or other,

such means of overcoming defects, discrepancies or errors will be accepted.

19.0 CORES :

19.1. The Core shall preferably be boltless and step lap design and CRGO to be

procured directly from CRGO supplier or from their accredited agent supported

by necessary documentary evidence for.

19.2. Core shall have magnite coating as insulation. Successful bidder will offer the

core for inspection and/or approval by the purchaser during manufacturing stage.

19.3. Manufacturer’s call notice for the purpose should be accompanied with the

following documents as applicable as a proof towards use of prime core

materials:

i) Invoice of the supplier

ii) Mill‟s Test Certificate

iii) Packing Lists

iv) Bill of landing

v) Bill of entry Certificate to Customs Core materials shall be procured either from

the core manufacturer or through their accredited marketing organisation of

repute. Bidder should preferably have in-house Core cutting facility for proper

monitoring and Control on quality. The materials used for insulation shall have

high inter lamination resistance and rust inhibiting property. It shall not have any

tendency to absorb moisture or to react with insulating oil.

19.4. The assembled core shall be securely clamped on the limbs and yoke with

uniform pressure so as to minimise noise emission form it.

19.5. The top main core clamping structure shall be connected to the tank body by a

copper strap. The bottom clamping structure shall be earthed by one or more of

the following methods

1. by connection through vertical tie rods to the top structure

2. by direct metal to metal contact with the tank base by the weight of the

core and windings,

3. by a connection to the top structure on the same side of core the main earth connection to the tank.

19.6. All parts of the cores shall be robust design capable of withstanding any shocks

to which they may by subjected during lifting, transport, installation and service.

19.7. Adequate lifting lugs shall be provided to enable the core and winding to be lifted.

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19.8. Adequate provision shall be made to prevent movement of the core and winding

relative to the tank during transport and installation or while in service.

19.9. The supporting frame work of the cores shall be so designed as to avoid the

presence of pockets which would prevent complete emptying of the tank through

the drain valve or cause trapping of air during filling.

19.10. The insulation structure for the core to bolts and core to clamp plates shall be

such as to withstand a voltage of 2000 VAC at 50HZ for one minute

.

20.0 FLUX DENSITY OF CORE

20.1. The maximum flux density in any part of the core and yokes at principal (normal)

tapping and at rated frequency shall not exceed 1.6 Tesla (16000 lines per

sq.cm) at normal voltage and 1.9 Tesla (19000 lines per sq.cm) under

overvoltage condition as specified in this specification.

20.2. Prior to inspection and testing of the Transformer the supplier shall submit on

request following curves of the core manufacturer.

i) Flux density vs Core loss.

ii) Flux density vs Excitatioin

21.0 WINDING:

21.1. All windings shall be fully insulated. 12.02 Power transformer shall be designed

to withstand the impulse and power frequency test voltages specified in clause

no. 9.01.

21.2. The windings shall be designed to reduce to a minimum the out of balance

forces in the transformer at all voltage ratios.

21.3. The insulation of Transformer winding and connections shall be free from

insulating material liable to soften, ooze out shrink or collapse and shall be non-

catalytic and chemically inactive to transformer oil during service.

21.4. The stacks of windings shall receive adequate shrinkage treatment before final

assembly. Adjustable device shall be provided for taking up any possible

shrinkage of coils in service.

21.5. All the insulating materials to be used in the transformer shall preferably be of

class- A insulation as specified in Indian Standards. The test certificate of the raw

materials shall be made available by the Transformer manufacturer on request

during inspection and testing.

21.6. The coil clamping arrangement and the finished dimensions of any oil ducts shall

be such that it will not impede the free circulation of oil through the ducts.

21.7. The windings and connection of transformer shall be braced to withstand shocks

which may occur during transport or due to switching short circuit and other

transient conditions during service.

21.8. Coil clamping rings, if provided shall be of steel or suitable insulating material.

Axially laminated material other than bakelised paper shall not be used.

22.0 INTERNAL EARTHING ARRANGEMENTS:

22.1. General : All metal parts of the transformer with the exception of the individual

core laminations, core bolts and associated individual clamping plates shall be

maintained at fixed potential.

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22.2. Earthing of coil clamping rings : Where coil clamping rings are of metal at

earth potential, each ring shall be connected to the adjacent core clamping

structure on the same side of transformer as the main earth connection.

23.0 TANKS:

23.1. Construction : Conventional type tank shall be constructed. The Transformer

tank and cover shall be fabricated from good commercial grade low Carbon steel

suitable for welding and of adequate thickness. The tanks of all transformers

shall be complete with all accessories and shall be designed so as to allow the

complete transformer in the tank and filled with oil, to be lifted by crane or jacks,

transported by rail, road without overstraining any joint and without causing

subsequent leakage of oil.

23.2. The main tank body shall be capable of withstanding vaccum gauge pressure

68.0 KN per Sq, metres ( 500 mm. of HG).

23.3. The under carriage of the tank shall be made of channel of suitable size and

design. The base of each tank shall be so designed that it shall be possible to

move the complete transformer unit by skidding in any direction without injury

when using plate or rails.

23.4. Where the base is of a channel construction, it shall be designed to prevent

retention of water. Tank stiffeners shall be designed to prevent retention of water.

23.5. Wherever possible the Transformer tank and its accessories shall be designed

without pockets wherein gas may accumulate. Where pockets cannot be

avoided, pipes shall be provided to vent the gas into the main expansion pipe.

23.6. All joints other than those which may have to be broken shall be welded when

required they shall be double welded. All bolted joints to the tank shall be fitted

with suitable oil tight gaskets which shall give satisfactory service under the

operating conditions and guaranteed temperature rise conditions. Special

attention shall be given to the methods of making hot oil tight joints between the

tank and the cover as also between the cover and bushing and all other outlets to

ensure that the joints can be remade at site satisfactorily.

24.0 TANK COVER

24.1. :Each tank cover shall be of adequate strength and shall not distort when lifted.

Inspection openings shall be provided as necessary to give easy access to

bushings or changing ratio or testing the earth connection. Each inspection

opening shall be of ample size for the purpose for which it is provided. The tank

cover and inspection cover shall be provided with suitable lifting arrangement.

24.2. The tank cover shall be fitted with pockets for thermometer and for the bulbs of

Oil and Winding temperature indicators. The thermometer pocket shall be fitted

with a captive screwed top to prevent the ingress of water. Protection shall be

provided, where necessary, for each capillary tube. The pocket shall be located

in the position of maximum oil temperature and it shall be possible to remove the

instrument bulbs without lowering the oil in the tank.

24.3. Turrets should provided on tank cover to house the bushings. The turrets of both

HV & LV bushings should be connected through pipes with main tank Buchholtz

Relay pipe to drive out trapped air or should have air release plug to drive out

trapped air as the case may be.

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25.0 OFF LOAD TAP CHANGER.

25.1. The transformers shall be provided with voltage control equipment of the tap

changing type on the HV side for HV variation of +3% to (-) 9% in equal 5 steps

of 3.0% for varying its effective transformation ratio whilst the transformers are

off-load. The tap changing device shall be off-circuit type. The tap changing shall

be carried out by means of an externally operated tapping switch capable of

being located and locked in any required position.

25.2. The location of tap changing device shall be such that an operator can very

easily change the tap, while standing on the ground without the aid of any

climbing platform. A warning plate indicating that switch shall not be operated in

“ON” position is to be provided.

25.3. The contact resistance between the contact points should be less than 20µΩ.

The manufacturer should show the resistance to the inspector at the time of

inspection.

26.0 CONSERVATOR VESSELS.

26.1. Conservator vessels : The conservator should be air cell/ atmoseal type to

prevent direct contact of Transformer oil with atmospheric air for retarding

oxidation contamination of oil. The Air cell shall be made from suitable material

with inner coating resistant to transformer oil & outer coating resistant to ozone &

weathering.

26.2. The conservator shall be provided with necessary valves to drive out the air in

the space between conservator wall & air cell during filling of oil, drain valves for

complete draining of oil and cut off valves etc.

26.3. The conservator complete with necessary valves shall be provided in such a

position as not to obstruct the electrical connections to the transformer from H.V

& L.V SIDE.

26.4. The conservator shall be a capacity to meet the requirement of expansion of the

total cold oil volume in the Transformer & cooling equipment.

26.5. The conservator shall be designed so that it can drain oil completely by means of

the drain valve provided when mounted. One end of the conservator shall be

bolted into position so that it can be removed for cleaning purpose.

26.6. The conservator shall be provided with different valves for filling of oil manually at

site.

27.0 OIL GAUGES

27.1. Normally one Magnetic type oil gage shall be provided. The oil level at 30 Deg.

C. shall be marked on the guage.

27.2. CONNECTION : The oil connection from the transformer tank to the conservator

vessel shall be arranged at a raising angle of 3 to 9 degrees to the horizontal up

to the Buchholtz Relay and shall consist of pipe with inside diameter 50 mm./80

mm. as per capacity of the Transformer and as per IS:3639 or equivalent

international specifications.

27.3. Two valves shall be provided between the conservator & Transformer main tank

to cut off the oil supply to the transformer after providing a straight run of pipe for

at least a length of five times the internal diameter of the pipe on the tank side

ofthe Gas and Oil actuated Relay and at least three times the internal diameter of

the pipe on the conservator side of the Gas and Oil actuated Relay. The valves

should be fitted on both side of the Gas and Oil Actuated Relay.

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28.0 BREATHER :

28.1. Each conservator vessel shall be fitted with a glass container type breather in

which silicagel is dehydrating agent and so designed that the passage of air

through the silicagel the external atmosphere is not continuously in contact with

the oil.

. The moisture absorption indicated by a change in colour of the tinted crystals can

be easily observed from the distance.

28.2. All breathers shall be mounted at approximately 1400 mm above ground level

and shall be connected to the air cell of the conservator through pipe for the

purpose of breathing during contraction or expansion of the air cell.

29.0 BUSHINGS

29.1. Bushings for 36 KV and below shall be of solid porcelain type. These bushings

shall be suitable for bare ACSR conductor connections.

29.2. The bushing shall have sufficient insulation to avoid leakage to ground and shall

be so located as to provide adequate electrical clearance between bushing or

various voltages and between bushings and grounded parts. The insulation class

of the high voltages neutral bushing shall be properly co-ordinated with the

insulation class of the neutral of the high voltage winding.

29.3. Stresses due to expansion and contraction in any part of the bushing insulator

shall not lead to the development of defects. Outdoor insulators and fittings shall

be unaffected by atmospheric conditions due to weather, fuses, ozone, acids,

dust and rapid changes of air temperature. Any stress shield shall be considered

as integral part of the bushing assembly.

29.4. Porcelain shall not engage directly with hard metal and where necessary gaskets

shall be interposed between the porcelain and the fittings. All porcelain clamping

surface in contact with gasket shall be accurately grounded and free from glaze

29.5. Fixing material used shall be of suitable quality and properly applied and shall not

enter into chemical action with the metal parts or cause fracture by contraction

expansion in service. Cement thickness shall be as small and even as possible

and proper care shall be taken to centre and locate individual parts correctly

during cementing. All porcelain insulators shall be designed to facilitate

clearance.

29.6. Each porcelain bushing or insulator, and paper bushing shall have marked upon

it the manufacturer‟s identification mark, and such other marks as may be

required to assist in the representative selection of batches for the purpose of the

sample tests.

29.7. Clamps and fittings shall be made of steel and galvanized. The bushing flanges

shall not be re-entrant type (shape) which may trap air.

29.8. Each bushing shall be so coordinated with the transformer insulation, that the

flashover will occur outside the tank.

29.9. All porcelain used in bushings shall be of wet process, homogeneous and free

from cavities or other flaws. The glazing shall be uniform in colour (brown) and

free from blisters, burns and other defects. Porcelain shall be thoroughly vitrified

and shall be impervious to moisture.

29.10. All bushing shall have puncture strength greater than dry flashover value.

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29.11. Creepage distance will be kept 27 mm/KV. Bushings may be provided with

weather shield.

29.12. The bidder is requested to give the guarantee withstand voltage for the above

and also furnish a calibration curve with different settings of the co-ordination

gap to enable the purchaser to decide the actual gap settings. Tenderer‟s

recommendations are also invited to this respect. During spark gap flashover, the

arc shall remain away from the housing insulator.

29.13. Each terminal (including neutral) shall be distinctly marked and coloured for

phase voltage and phase rotation on the primary secondary and tertiary sides in

accordance with the diagram of connection supplied with the transformer, the

system of marking shall conform IS 2026-1962 amended upto date.

29.14. Stress due to expansion and contraction in any part of the bushing shall not lead

to deterioration.

29.15. Bushing shall be designed and tested to comply with the applicable standards.

29.16. Bushings rated for 400A and above shall have non-ferrous flanges and hardware.

29.17. Fittings made of steel or malleable iron shall be galvanized.

29.18. Bushing shall be so located on the transformer that full flashover strength will be

utilized. Minimum clearances as required for the BIL shall be realized between

live parts and live parts to earthed structures.

29.19. All applicable routine and type tests certificates of the bushings shall be furnished

for approval.

29.20. Bushings shall be supplied with bimetallic/terminal connectors/ clamp suitable for

fixing to bushing terminal and the PURCHASER‟S specified conductors. The

connectors/clamp shall be rated to carry the bushing rated current without

exceeding a temperature rise of 55° C over an ambient of 40° C. the connector/

clamp shall be designed to be corona free at the maximum rated line to ground

voltage.

29.21. Bushing of identical voltage rating shall be interchangeable.

29.22. Each bushing shall be so coordinated with the transformer insulation that all

flashover will occur outside tank.

30.0 FILTER AND DRAIN VALVES, SAMPLING DEVICES AND AIR RELEASE PLUGS :

30.1. Each Transformer shall be fitted with the following :

30.2. The filter and drain valves as specified.

A drain valve as below shall be fitted to each conservator. For diameter upto 650

mm : Size of the valve 15 mm : for diameter above 650 mm : Size of the valve 25

mm.

Suitable oil sampling device shall be provided at the top and bottom of the main

tank. The sampling device shall not be fitted on the filter valves specified above.

One 15mm air release plug on the main tank of the Transformer.

30.3. All other valves opening to atmosphere shall be fitted with blank flanges.

Valves shall be of forged carbon steel upto 50 mm size and of gun metal or of cast iron bodies with gun metal fittings for sizes above 50 mm. They shall be of full way type with screwed ends and shall be opened by turning counter clock

24

wise when facing the hand wheel. There shall be no oil leakage when the valves are in closed position.

30.4. Each valve shall be provided with an indicator to show the open and closed

position and shall be provided with facility for padlocking in either open or closed

position. All screwed valves shall be furnished with pipe plugs for protection.

Padlocks with duplicate keys shall be supplied along with the valves.

30.5. All valves except screwed valves shall be provided with flanges having machined

faces drilled to suit the applicable requirements. Oil tight blanking plates shall be

provided for each connection for use when any radiator is detached and for all

valves opening to atmosphere. If any special radiator valve tools are required, the

Contractor shall supply the same.

30.6. Each transformer shall be provided with following valves on the tank so located

as to completely drain the tank.

Two filter valves on diagonally opposite corners, of 50 mm size.

Oil sampling valves not less than 8 mm at top and bottom of main tank

30.7. Valves between radiators and tank.

30.8. Valve prior to and after the Buchholz Relay.

31.0 COOLING PLANT

31.1. General :Radiators shall be so designed as to avoid pockets in which moisture

may collect and shall withstand the pressure tests.

31.2. The radiator tubes / fins shall be seamless, made of mild steel having as

minimum wall thickness of approx. 1.2mm and a clean bright internal surface free

from dust and scale. They shall be suitably braced to protect them from

mechanical shocks, normally met in transportation and to damp the modes of

vibration transmitted by the active part of the transformer in service.

31.3. Each cooler unit shall have a lifting eye.

31.4. Radiator Valves: The butterfly or similar metal valves shall be provided for

isolating detachable radiator assembly.

31.5. One cock each at the bottom of radiator stack shall be provided for draining oil

from radiator stacks.

31.6. Air release plug each at the top of radiator stack shall be provided for release of

air from radiator stack.

31.7. Removable blanking plates shall be provided to permit the blanking off the main

oil Connection of each cooler.

31.8. Radiator fixing bands in top & bottom of radiators are to be provided to minimise

the vibration of the same.

32.0 LIFTING AND HAULAGE FACILITY :

32.1. Each tank shall be provided with Lifting lugs suitable for lifting of transformer

complete with oil.

32.2. A minimum of four jacking lugs, in accessible positions to enable the transformer

complete with oil to be raised or lowered using hydraulic or screw jacks .

32.3. The minimum height of the lugs above the base shall be as follows

(a) for transformers up to and including 10 tones weight-300mm

(b) for Transformers above 10 tones weight – 500 mm

32.4. Suitable haulage holes shall be provided.

25

33.0 INSULATING OIL :

33.1. The Transformer and all associated oil filled Equipment shall be supplied

complete with insulating new oil required for first filling including 10% extra oil for

future use during commissioning. The Transformer tank shall be dispatched

completely filled with oil and the balance oil shall be supplied in non returnable

sealed drums along with the Transformers.

33.2. The Insulating oil shall conform to the requirement of IS:335 or equivalent

international specifications.

34.0 PRESSURE RELIEF DEVICE :

34.1. Pressure relief device shall be provided of sufficient sizes for rapid release of

pressure that may by generated within the tank, and which might result in

damage to the equipment. The device shall operate at a static pressure of less

than the hydraulic test pressure for transformer tank. Means shall be provided to

prevent ingress of rain.

34.2. It shall be mounted on the cover of the main tank and shall be designed to

prevent gas accumulation.

34.3. Spring loaded setting type Pressure Relief Valve having suitable opening Port

hole according to the capacity of the transformers should be provided.

34.4. The pressure relief valve should have provision of visual indication for opening of

the valve and also Contract/Micro Switch arrangement for alarm/Tripping

Function.

35.0 AXLES AND WHEELS :

35.1. The Transformer shall be provided with flanged bi-directional wheels as

mentioned below :

Flanged wheel suitable for use on a 1435 mm / 1676 mm guage track.

. 35.2. The wheels shall be suitable for being turned through an angle of 90 Deg. and

locked in that position when the tank is jacked up.

35.3. All wheels shall be detachable and shall be made of Cast Iron or Steel. Suitable

locking arrangement shall be provided to prevent the accidental movement of the

transformer.

36.0 CLEANING & PAINTING

36.1. Before painting or filling with oil all galvanised parts shall be completely cleaned

and free from rust, scale and grease and all external surface cavities on castings

shall be filled by metal deposition.

36.2. The interior of all transformer tanks and other oil filled chambers and internal

structural steel work shall be thoroughly cleaned of all scale and rust by sand

blasting or other approved method. These surfaces shall be painted with hot oil

resisting varnish or paint. Unexposed welds need not be painted.

26

36.3. Except for nuts, bolts and washers, which may have to be removed for

maintenance purposes, all external surfaces shall receive a minimum of three

coats of paint.

36.4. The primary coat shall be applied immediately after cleaning. The second coat

shall be of oil paint of weather resisting nature and preferably of a shade or

colour easily distinguishable from the primary and final coasts shall be applied

after the primary coats have been touched up where necessary.

36.5. The final coat shall be of glossy oil and weather resisting non fading paint of Dark

Admiralty Grey shade no. 632 of IS:5.

36.6. Primer paint shall be ready made zinc chrome as per IS: 104: Intermediate and

final coats of paint shall be as per IS: 2932 or equivalent international

specifications.

36.7. All interior surfaces of mechanism chambers and kiosks except those which have

received anti-corrosion treatment shall receive three coats of paint applied to the

thoroughly cleaned metal surface as per procedure mentioned above. The final

coat shall be of a light coloured anti-condensation mixture.

36.8. Any damage to paint work incurred during delivery shall be made good by the

manufacturer by thoroughly cleaning the damage portion and applying the full

number of coats of paint that had been applied before the damage was caused.

37.0 EARTHING TERMINAL

37.1. Two earthing terminals capable of carrying the full amount of lower voltage short

circuit current of transformer continuously for a period of 5 Second Provision

shall be made at positions close to each of the bottom two corners of the tank for

bolting the earthing terminals to the tank structure to suit local condition.

38.0 TEMPERATURE INDICATING DEVICE:

38.1. Oil temperature indicator with two electrical contacts for alarm and trip

purposes, shall be provided with anti vibration mounting. The oil temperature

indicator shall be housed in the marshalling box.

38.2. The winding temperature indicator with two electrical contacts for alarm & trip

purposes shall be provided with anti vibration mounting. The winding temperature

indicator shall be housed in the marshalling Box.

38.3. The Oil and Winding temperature indicator should be of renowned make

preferably of “Perfect Control” or “Precimeasure”. The scale on the dial of the

thermometer should be 0°C to 150°C. The angular displacement of thermometer

should be 270 Deg.

38.4. The signaling contact of WTI & OTI shall be set to operate at the following

temperature:

OIL : Alarm-85 °C, Trip – 95 ° C WINDING : Alarm-100 °C, Trip – 110 °C

38.5. The tripping contacts of indicator shall be adjustable to close the winding

temperature indicator between 60 Deg.C and 120 Deg.C. The alarm contacts of

indicator shall be adjustable to close between 50 deg.C & 100 Deg.C.

27

38.6. All contacts shall be adjustable on a scale and shall be accessible on removal of

the cover. The Temperature indicators shall be so designed that it shall be

possible to check the operation of contacts and associated Equipments.

38.7. For measuring winding temperature a heater coil fed from a C.T. has to be

provided on the pocket for winding temperature indicator bulb. The connection

from C.T. to heater should be through a link arrangement on the tank cover

suitably housed in a weather proof box so that C.T. current and heater coil

resistance can be checked. WTI C.T. secondary should be of 5 Amps, rating.

38.8. Accuracy class of both OTI and WTI shall be ±1% or better.

39.0 MARSHALLING BOX

39.1. A sheet steel 3.15mm thick vermin proof, well ventilated and weather proof

marshalling box of a suitable construction shall be provided for the

transformer ancillary apparatus. The box shall have domed or sloping roofs

and the interior & exterior painting shall be in accordance with painting

clause specified. The degree of protection shall be IP-55.

39.2. The marshalling box shall accommodate.

Winding and oil temperature indicator.

Terminal Blocks and gland plates for incoming and outgoing Cables.

One space heater operated by 220 V.A.C. Aux. Supply, Cubicle illuminating lamp

with door switch.

39.3. All incoming cables shall enter the kiosk from the bottom and the gland

plate shall not be less than 450 mm from the base of the box. The gland

plate and associated compartment shall be sealed in suitable manner to

prevent the ingress from the cable trench

39.4. All the above equipment shall be mounted on panels and back of panel

wiring shall be used for Interconnection. The temperature indicators shall be

so mounted that the dials are visible by standing at ground level.

39.5. Door of the compartment shall be provided with glass window of adequate

size. Ventilation louvers shall be provided.

39.6. The schematic diagram of the circuitry inside the marshalling box be

prepared and fixed inside the door

40.0 GAS AND OIL ACATUATED RELAYS

40.1. Each transformer shall be provided with gas and oil actuated Relay (Buchholtz

Relay) equipment conforming to IS:3637 or equivalent international specifications,

double float type with one set of alarm contacts, one set of trip contacts and a

testing pet cock. The contacts shall be wired with a P.V.C. armoured cable.

40.2. A machined surface shall be provided on the top of Relay to facilitate the setting of

Relay and to check the mounting angle in the pipe and cross level of the Relay.

28

40.3. The pipe work shall be so arranged that all gas arising from the Transformer shall

pass into the gas and oil actuated Relay. The oil circuit through the Relay shall not

form a delivery path in parallel with any circulating oil pipe.

41.0 RATING DIAGRAM AND PROPERTY PLATES :

41.1. The following plates shall be fixed to the transformer tank at a suitable height so

that the particulars could be read by standing at ground level.

41.2. A rating plate bearing the data specified in the relevant clauses of IS:2026

including figures of temperature rise of oil and winding and high voltage test values.

that the equipment belongs to APDCL with reference of purchase order is also to

be indicated.

41.3. A diagram plate showing the internal numbering of taps, tapping switch connection

of windings and also the voltages vector relationship in accordance with IS:2026 or

equivalent international specifications and in addition a plan view of the transformer

giving the correct physical relationship of the terminals. No load voltage shall be

indicated for each tap. Details of C.T particulars w.r.o phase, Neutral &WTI CT.

42.0 CENTRE OF GRAVITY :

42.1. The centre of gravity of the assembled transformer shall be low and as near the

vertical centre line as possible. The transformer shall be stable with or without oil.

42.2. If the centre of gravity is eccentric relative to track either with or without oil, its

location shall be shown on the outline drawing.

43.0 FOUNDATION :

43.1. The tenderer shall furnish foundation plan of the transformer showing the fixing

arrangement of the transformer so that the purchase may be able to finalise the

foundation drawings.

44.0 TEST AND INSPECTION :

44.1. Routine Tests :

44.2. All transformers shall be subjected to the following routine tests at the

manufacturer‟s works. The tests shall be carried out in accordance with the

details specified in IS:2026 or equivalent international specifications.

i. Measurement of winding resistance.

ii. Measurement of turns ratio for all sets wndings on each tap

iii. Polarity and phase vector relationship.

iv. Measurement of no load loss and no load current.

v. Measurement of impedance voltage at normal , maximum and minmum tap

vi. Measurement of insulation resistance between windings and between windings and earth

vii. Measurement of load loss

viii. Induced over voltage withstand test

ix. Separate source voltage withstand test

29

x. Oil Leakage gas collection, oil surge and voltage test on gas and oil actuated relay for on load tap changer

xi. Magnetic balance test

xii. Testing of Phase & Neutral C.T., as applicable, in accordance with provisions in the relevant I.S

xiii. Oil leakage test of tnansformer tanks at a pressure equals to the normal pressure plus 35 KN/ sq.M measured at the base of tank

.

44.3. Type Test

44.4. In addition to routine Tests mentioned above the transformer shall be subjected

to all kinds of Type and Acceptance Test in accordance with Relevant I.S.

(IS:2026) or equivalent international specifications with latest amendment if any.

44.5. Bidder should submit Type Test report from NABL/Govt. approved

Laboratories along with their offer having identical technical parameters as

that of the tendered item failing which their offer may not be technically

accepted.

44.6. However, if it is found that the bidder has submitted Type tests Report but

those have not been conducted on identical Design of equipment/material

as per specification of APDCL, the same may be accepted subject to the

following conditions: APDCL at his discretion request the successful

bidders to conduct Type Tests on identical design as per specification

44.7. . Such Type tests/special tests, if required to be carried out at NABL/Govt.

approved Laboratories in presence of APDCL engineers for which no extra

cost shall be charged to the APDCL.

44.8. However, the bidders who have not submitted such Type Test/Dynamic Short

Circuit Test report but if their offer is considered technically acceptable by the

purchasers on the basis of other credentials, they will have to carry out such tests

at NABL/Govt. approved Laboratories in presence of APDCL engineers before

effecting physical delivery against Purchase Order for which no extra cost shall

be charged to the APDCL. Routine Test have to be carried out in presence of

APDCL engineers before carrying out type test.

45.0 INSPECTION AND TESTING

(A) STAGE INSPECTION

Stage inspections of raw materials i.e. Tank, Core, Winding, Bushing, Insulating Materials

etc. will be carried out in preassembled condition and final inspection will be carried out

on finished product.

Out of the whole lot of respective capacity, one

Transformer will be dissembled for verification of design parameter during final

inspection.

a) Tank and Conservator

(i). Inspection of major weld.

30

(ii). Crack detection of major strength weld seams by dye penetration test.

(iii). Check correct dimensions between wheels, demonstrate turning of wheels, through 90o and further dimensional check

(iv). Leakage test of the conservator.

(v). Measurement of film thickness of :

Oil insoluble varnish.

Zinc chromate paint.

Finished coat.

(vi). Tank pressure test

(vii). Vacuum test

b) Core

(i). Sample testing of core materials for checking specific loss properties, magnetisation characteristics and thickness.

(ii). Check on the quality of varnish if used on the stampings.

(iii). Check on the amount of burrs.

(iv). Visual and dimensional check during assembly stage.

(v). Check on completed core for measurement of iron loss.

(vi). Visual and dimensional checks for straightness and roundness of core, thickness of limbs and suitability of clamps.

(vii). High voltage test (2 kV for one minute) between core and clamps.

c) Insulating Material

(i). Sample check for physical properties of materials.

(ii). Check for dielectric strength

(iii). Check for the reaction of hot oil on insulating materials.

d) Winding

(i). Sample check on winding conductor for mechanical and electrical conductivity.

(ii). Visual and dimensional checks on conductor for scratches, dentmark etc.

(iii). Sample check on insulating paper for PH value, electric strength.

(iv). Check for the bonding of the insulating paper with conductor.

(v). Check for the reaction of hot oil and insulating paper.

(vi). Check and ensure that physical condition of all materials taken for windings is satisfactory and free of dust.

(vii). Check for brazed joints wherever applicable.

(viii). Check for absence of short circuit between parallel strands.

e) Checks Before Drying Process

(i). Check condition of insulation on the conductor and between the windings.

(ii). Check insulation distance between high voltage connections, between high voltage connection cables and earth and other live parts.

(iii). Check insulating distances between low voltage connections and earth and other parts.

(iv). Insulating test for core earthing.

31

f) Checks During Drying Process

(i). Measurement and recording of temperature and drying time during vacuum treatment.

(ii). Check for completeness of drying.

g) Assembled Transformer

(i). Check completed transformer against approved outline drawing, provision for all fittings, finish level etc.

(ii). Jacking test on the assembled Transformer.

h) Oil

All standard test in accordance with IS: 335 shall be carried out on Transformer oil sample before filling in the transformer.

i) Test Reports for bought out items

The contractor shall submit the test reports for all bought out/sub contracted items for approval. All auxiliary equipment shall be tested as per the relevant IS & IEC. Test certificates shall be submitted for bought out items.

(i). Bucholz relay (ii). Winding temperature indicators. (iii). Oil temperature indicators. (iv). Bushings (v). Marshalling box (vi). Air Cell (vii). Thermosyphon filter (viii). Off Load Tap changer (ix). Any other item required to complete the works.

(B) Final Inspection: During final inspection all routine tests mentioned in clause 44.2

shall be carried out at the factory of the manufacturer in presence of the Inspecting officer of APDCL

Temperature rise test: temperature rise test in any one of the transformer of each lot is to be performed in presence of the Inspecting officer of APDCL

46.0 Porcelain, bushings, control devices, insulating oil and other associated equipment shall be

tested by the contractor in accordance with relevant IS. If such equipment are purchased by

the contractor on a sub-contract, he shall have them tested to comply with these

requirements

46.1. Inspection and testing as already mentioned the equipment shall be subjected to

routine and other acceptance tests as per provisions in the relevant I.S.

46.2. The APDCL reserves the right to send its Engineers if so desires to witness

manufacturing process and to reject either raw materials or finished products

found to be not complying with the requirement of the specification and also shall

have the right to select any/all equipment from the lot offered for tests.

46.3. The manufacturer shall give at least (21) twenty one days’ advance notice

regarding readiness of such inspection and testing and shall submit six sets of

the works test certificates of the materials/equipment offered for inspection and

testing indicating probable date of inspection and testing.

46.4. The manufacturer shall arrange all possible facilities for such inspection and

testing at any time during the course of manufacture free of cost.

32

47.0 TEST CERTIFICATE

Five copies of the approved Test Certificates as mentioned above are to be

furnished to the APDCL before dispatch of the equipment.

48.0 DRAWINGS AND MANUALS TO BE SUBMITTED BY SUCCESSFUL BIDDER

48.1. The bidder shall furnish, within fifteen days after issuing of letters Award, six

copies each of the following drawings/documents incorporating name of project

and transformer rating for approval.

i. Detailed overall general arrangement drawing showing front and side elevations and plan of the transformer and all accessories including radiators and external features with details of dimension, spacing of wheels in either direction of motion, net weights and shipping weights, crane lift for untanking, size of lugs and eyes, bushing lifting dimensions, clearances between HV and LV terminals and ground, quantity of insulating oil etc.

ii. Foundation plan showing loading on each wheel and jacking points with respect to centre line of transformer.

iii. GA drawing/details of bushing and terminal connectors.

iv. Name plate drawing with terminal marking and connection diagrams.

v. Wheel locking arrangement drawing.

vi. Transportation dimension drawings.

vii. Interconnection diagrams.

viii. Over fluxing withstand time characteristics of transformer.

ix. GA drawing of marshalling box.

x. Control scheme/wiring diagram of marshalling box.

xi. Technical leaflets of major components and fittings.

xii. As built drawing of schematic, wiring diagrams etc.

xiii. Setting of oil temperature indicator, winding temperature indicator.

xiv. Completed technical data sheets.

xv. HV/LV conductor bushing.

xvi. Bushing assembly.

xvii. Bi-metallic connector for connection to “Wolf”/PANTHER ACSR/AAAC conductor

xviii. Radiator type assembly.

48.2. All drawings/documents, technical data sheets and test

certificates/results/calculations shall be furnished.

48.3. Any approval given to the detailed drawings by the purchaser shall not

relieve the contractor of the responsibility for correctness of the drawing

33

and in the manufacture of the equipment. The approval given by the

purchaser shall be general with overall responsibility with contractor.

48.4. Installation, operation and maintenance manual of transformer, associated

equipment like buchholtz Relay, temperature indicators, oil level indicator

etc. The manual shall clearly indicate the installation method, check-ups

and tests to be carried out before and after commissioning of the

transformer.

48.5. One copy of manual, set of approved drawings shall be submitted to the

CGM(PPD)/APDCL before dispatch of the Transformer.

48.6. In addition one set of approved drawing, manual for transformer shall be

send to the respective consignee officer in water proof folder at the time of

delivery of the transformer.

49.0 GUARANTEED TECHNICAL PARTICULARS

Bidder shall furnish guaranteed technical particulars of equipment offered as per

Schedule „B‟ To be provided along with final NIT specification),

50.0 ACCESSORIES

All accessories as specified in the schedule A are to be provided. Any other part

necessary for smooth operation of the transformer if omitted it is the

manufacturers responsibility to include the same.

51.0 SPARE PARTS:

The Tenderer shall submit a recommended list of spare parts for five years of

operation along with item wise price for each item of spares as stated in

Schedule B

34

SCHEDULE – A

FITTINGS & ACCESSORIES

The following fittings and accessories shall be supplied with each Transformer :

1. Outdoor type bushing – HV-3 Nos. and LV-4 Nos.

2. Conservator with aircell and supporting bracket or structure as the case may be.

3. Isolating valve for conservator in between conservator and Buchholtz Relay and

in between Buchholtz relay and main tank..

4. Conservator valves for driving out air between air cell & wall of conservator &

connection to breather.

5. Conservator drain valve.

6. Dial type oil level indicator complete with alarm contact.

7. Silica gel breather with oil seal and connecting pipe. The breather shall be

accessible for inspection from ground.

8. Spring loaded setting type pressure relief Valve having suitable opening Port.

Hole & provision of visual indication for opening of the valve & Alarm/Trip contact

arrangement.

9. Access/inspection holes with bolted cover for access to inner ends of bushing.

10. Cover lifting eyes.

11. Lifting eyes for core frame with windings.

12. Tap changing arrangement with hand wheel for Off-Load tap-

13. Air release plugs on top of cover and pressure equalizer pipe for bushing turret.

14. Upper filter valve and bottom filter valve.

15. Drain valve.

16. Top and bottom oil sampling devices. Provision for oil sample collection during

process of filtration should be made.

17. Lifting lugs.

18. Jacking pads with handling holes at four corners.

19. Transport lugs.

20. Under carriage base channel.

21. Tank earthing terminals – 2 Nos.

22. Buchholtz relay double float type with one set of alarm contacts, one set of trip

contacts and testing pet cock. The contacts should be wired with a PVC

armoured cable

23. Dial thermometer for winding temperature with alarm contacts and Trip contacts.

24. Dial thermometer for oil temperature with alarm contacts and Trip Contacts.

25. An additional pocket for inserting thermometer for oil temperature indication.

26. Weather proof control cabinet for marshalling terminal connections from

protective and indicative devices. The cabinet shall be provided with

incandescent filament lighting, heater and plugs etc.

27. Rating plate, as per I.S.S

28. Diagram Plate :

29. Property label

35

SCHEDULE – B

SPARE PARTS:

The mandatory spare parts shall include but not be limited to the following for each rating of transformer.

(i) Bushings:

a. High Voltage - 1 No.

b. Low Voltage - 1 No.

c. Neutral Bushing - 1 No.

(ii) Complete set of gaskets for all - 1 Set openings on the tank requiring gasket.

(iii) Magnetic oil level gauge with low oil - 1 No. level alarm contacts.

(iv) Oil temperature indicator with alarm - 1 No. and trip contacts and maximum reading pointer.

(v) Winding temperature indicator with alarm and trip - 1 No. contacts and maximum reading pointer

(vi) Set of all types of valves comprising one in each type. - 1 Set

(vii) Silicagel breather - 1 No.

(viii) Buchholz Relay - 1 No.

Note: The quantities indicated above are for each transformers.

36

Guaranteed Technical Particulars

GUARANTEED TECHNICAL PARTICULARS OF 33kV /11kV TRANSFORMER (To be filled by bidder)

Sl. No

Description

1 Name of the Manufacturer

2 Installation [indoor/outdoor]

3 Reference standards

4 Continuous Ratings

a) Type of cooling

b) Rating [MVA]

c Rated voltage

i HV [KV rms.]

ii LV [KV-rms.]

d Highest system voltage

i HV [KV rms.]

ii LV [KV-rms.]

e Rated frequency with ±% variation

f Number of phases

g Current at rated full load and on principal tap

i HV [Amps]

ii LV [Amps]

5 Connections

HV

LV

6 Connection symbol and vector group

7 Temperature rise

a Temperature rise of oil above reference peak ambient temperature i.e.50 °C [by thermometer] [°C]

b Temperature rise of winding above reference peak ambient temperature [by resistance method][°C]

c Temperature gradients between windings & oil.

d Limit of Hot spot temperature for which the Transformer is designed [°C]

8 Type of OFF load tap changing switch

9 Tapping on windings for

i Constant flux/variable flux/combined regulation

ii Tapping provided at

iii Number of steps

iv Range of tapping for variation [+ percent to - percent]

10 i No load loss at rated voltage and frequency at principal tap [KW]

ii No load loss at the voltage corresponding to highest tap [KW]

11 Load loss at rated output, rated frequency, corrected for 75 °C winding temperature at:- [Copper loss ]

ONAN

37

i Principal tap [In KW]

ii Highest tap [In KW]

iii Lowest tap [In KW]

12 Positive sequence impedance on rated MVA base at rated current and frequency at 75°Centigrade winding temperature at

i Principal tap [%]

ii Highest tap [%]

iii Lowest tap [%]

13 Zero sequence impedance at reference temperature of 75°C at principal tap [%]

14 % reactance at rated MVA base at rated current and rated frequency at

i Principal tap [%]

ii Highest tap [%]

iii Lowest tap [%]

15 % resistance at rated MVA base at rated current and rated frequency at

i Principal tap [%]

ii Highest tap [%]

iii Lowest tap [%]

16 % Impedance at rated MVA base at rated current and rated frequency at

i Principal tap [%]

ii Highest tap [%]

iii Lowest tap [%]

17 a Polarisation index i.e. ratio of Megger values at 600 secs to 60 secs, (H.V. to E, L.V. to E, & H.V.to L.V.)

In Between PI

H.V - E

L.V. - E

H.V – L.V.

b Regulation at full load and 75°C winding temperature expressed as a percentage of normal voltage

i At unity power factor [%]

ii At 0.8 power factor [lagging][%]

18 Efficiency at 75°C winding temperature as derived from guaranteed loss figures and at

Unity power factor

0.8 Power factor

a At full load [%]

b At ¾ load [%]

c At ½ load [%]

19 i Maximum efficiency [%]

ii Load at which maximum efficiency occurs[% of full load]

20 Short time thermal rating of

i HV winding in KA and duration in seconds

ii LV winding in KA and duration in seconds

21 Permissible over loading:-

a HV winding

b LV winding

22 Terminal arrangement

a High voltage [HV]

b Low voltage (LV)

c Neutral

23 Insulating and cooling medium

24 Test voltage HV LV

38

i Lightning impulse withstand test voltage [KVP]

ii Power frequency withstand test voltage [dry and wet][for 1 minute] [KV-rms.]

25 Noise level when energized at normal voltage, frequency without load.

26 External short circuit withstand capacity [MVA] and duration [seconds]

27 Over-fluxing withstand capability of the Transformer

28 DETAILS OF CORE

a Type of core construction

b Type of corner joints of the core

c Maximum flux density at

i Rated voltage [33/11 KV] & rated frequency 50 Hz][in Tesla]

ii Highest system voltage [36/12 KV] and lowest system frequency [48.5Hz.][in Tesla]

d No load current, no load loss and no load power factor at normal ratio and frequency [Amp/KW/p.f.]

i 10 percent of rated voltage

ii 25 percent of rated voltage

iii 50 percent of rated voltage

iv 85 percent of rated voltage

v 100 percent of rated voltage

vi 105 percent of rated voltage

vii 110 percent of rated voltage

viii 112.5 percent of rated voltage

ix 115 percent of rated voltage

x 120 percent of rated voltage

xi 121 percent of rated voltage

xii 125 percent of rated voltage

e Core laminations:-

i Material of core lamination [M4 /HIB]

ii Grade of core laminations

iii Thickness of core lamination [mm]

iv Specific loss [watt/Kg.] at rated voltage and rated frequency

v Specific loss [watt/Kg.] at highest system voltage and lowest system frequency

vi Whether specific core loss graph [flux density vs. watt/Kg. submitted

vii VA/Kg at rated voltage and rated frequency

viii VA/Kg. at highest system voltage and lowest system frequency

ix Whether VA/Kg. Vs. flux density graph Submitted

x Insulation of core laminations

f CORE ASSEMBLY:-

i Core diameter [mm]

ii Core window height [mm]

iii Core leg centre [mm]

iv Gross core cross-sectional area [m²]

v Whether details of core widths, stacks

39

and calculation furnished as per enclosed annexure

vi Distance between centers [mm]

vii Total height of core [mm]

viii 1) Details of core belting.

2) Material, grade & type

3) Width

4) Thickness

5) Fixing method

ix Details of top end frame

x Details of Bottom end frame

xi Details of clamp plate [Material, thickness, Insulation]

xii Total core weight [kg]

xiii Core loss basing on core loss graph at operating flux density [rated voltage and rated frequency] [kw]

xiv Core stacking factor

xv Net core area Sq. m.

xvi Margin towards corner joints, cross fluxing etc [kw]

xvii Total core loss at rated voltage and rated frequency [xiii+xvii] [kw]

xviii Dielectric loss at rated voltage and rated frequency [KW]

xix No load loss at rated voltage and rated frequency [xviii+xix] [KW]

g Describe location/method of core grounding

h Details of oil ducts in core

i Peak value of magnetizing Inrush current (% of HV rated current).

29 DETAILS OF WINDINGS. HV Regulating LV

a Type of winding

b Material of the winding conductor

c Maximum current density of windings [at rated current] and conductor area

Conductor area [cm²]

Current density [A/cm²]

i HV

ii Regulating

iii L.V.

d Whether HV windings are interleaved

e Whether windings are pre-shrunk?

f Whether adjustable coil clamps are provided for H.V. and L.V. windings?

g Whether steel rings are used for the windings? If so, whether these are split?

h Whether electrostatic shields are provided to obtain uniform voltage distribution in the windings?

i Winding Insulation. Type & class Graded or Ungraded

i H.V. & Regulating

ii LV Winding

j Insulating material used for

i H.V.& Regulating winding

ii L.V Winding

iii Tapping connection

k Insulating material used between

40

i H.V. and L.V. winding

ii H.V. and Regulating winding

iii Core and L.V winding

iv L.V. Winding and core

v Regulating Winding and core

vi H.V. winding and core

vii H.V. to H.V. winding [between phases]

l Type of axial coil supports

i H.V. winding

ii Regulating winding

iii LV winding

m Type of radial coil supports

i H.V. winding

ii Regulating winding

ii LV winding

n Maximum allowable torque on coil clamping HV Regulating LV bolts

o Bare conductor size (mm).

p Insulated conductor size (mm).

q No. of conductors in parallel (Nos.).

r No. of turns/phase

s No. of discs/phase

t No. of turns/disc

u Gap between discs. (mm).

v Inside diameter (mm).

w Outside diameter (mm).

x Axial height after shrinkage (mm).

y D.C.RESISTANCE

i L.V winding at 75 ° C (Ohms).

ii HV winding and Regulating winding at normal tap at 75° C (Ohms).

iii HV winding and Regulating winding at highest tap at 75° C (Ohms).

iv HV winding and regulating winding at lowest tap. (Ohms).

v Total I²R losses at 75 ° C. for normal tap. (KW).

vi Total I²R losses at 75 ° C. for highest tap. (KW)

vii Total I²R losses at 75 ° C for lowest tap.(KW).

viii Stray losses including eddy current losses in winding at 75°C (KW).

a Normal tap position

b Highest tap position

c Lowest tap position.

d Any special measures taken to reduce eddy current losses and stray losses, mention in details

x Load losses at 75°C [I²R + stray].

a Normal tap position [KW].

b Highest tap position [KW].

c Lowest tap position [KW].

z Details of special arrangement provided to improve surge voltage distribution in the windings

30 BUSHINGS. HV LV Neutral

a Make and type

41

i Rated voltage class [KV-rms.]

ii Rated current [Amps.]

b Lightning Impulse withstand test voltage [1.2/50 micro second][KVP]

c Power frequency withstand test voltage

i Wet for 1 minute [KV-rms]

ii Dry for 1 minute [KV-rms]

d Power frequency visible corona discharge voltage [KV-rms.]

e Minimum creepage distance in mm

f Phase to earth clearance in air of live parts at the top of bushings

31

Minimum clearance [mm]

In Oil Out of Oil

Between windings

Phase to

Ground

Between windings

Phase to

Ground

HV

LV

32 Weight [Tolerance + 5%] [Approximate value is not allowed]

a Core [Kg.]

b Core with clamping [Kg.]

c H.V. winding insulated conductor [Kg.]

d Regulating winding insulated conductor [Kg.]

e L.V.winding insulated conductor [Kg.]

f Coils with insulation [Kg.]

g Core and winding [Kg]

h Oil required for first filling [Liter/Kg.]

i Tank and fittings with accessories [Kg.]

j Untanking weight [Kg.]

k Total weight with oil and fittings [kg.]

33 DETAILS OF TANK

a Material for Transformer tank

b Type of tank

c Thickness of sheet [No approximate value to be mentioned]

i Sides [mm]

ii Bottom [mm]

iii Cover [mm]

iv Radiators [mm]

d Inside dimensions of main tank [No approximation in dimensions to be used]

i Length [mm]

ii Breadth [mm]

iii Height [mm]

e Outside dimensions of main tank [No approximation in dimensions to be used]

i Length [mm]

ii Breadth [mm]

iii Height [mm]

f Thickness of spray galvanisation of tank bottom.

g Vacuum recommended for hot oil circulation [torr]

h Vacuum to be maintained during oil

42

filling in Transformer tank [torr]

i Vacuum to which the tank can be subjected without distortion [torr]

j No. of bi-directional wheels provided

k Track gauge required for the wheels

i Transverse axis

ii Longitudinal axis

l Type and make of pressure relief device and minimum pressure at which it operates [Kpa]

34 CONSERVATOR

a Total volume [Liters]

b Volume between the highest and lowest visible oil levels [Litres]

c Whether flexi separator provided

35 OIL QUALITY

a Governing standard

b Density in gms/cu-cm

c Kinematics viscosity in CST

d Inter facial tension at 27°C in N/m

e Flash point in °C

f Pour point in °C

g Acidity [neutralization value] in mg of KOH/gm

h Corrosive sulfur in %

i Electric strength [breakdown voltage]

i As received [KV-rms.]

ii After treatment [KV-rms.]

j Dielectric dissipation factor [tan delta] at 90°C

k Saponification value in mg of KOH/gm

l Water content in ppm

m Specific resistance

i At 90°C [ohm-cm]

ii At 27 °C [ohm-cm]

N- dm analysis

CA%

CM%

CP%

o Oxidation stability

i Neutralization value after oxidation

ii Total sludge after oxidation

p Characteristic of oil after ageing test as per ASTMD-1934

i Specific resistance at

27°C [ohm-cms]

90°C [ohm-cms]

ii Tan delta

iii Sludge content

iv Neutralization number

v Details of oil preserving equipment offered

36 RADIATORS

a Overall dimensions lxbxh [mm]

b Total weight with oil [Kg.]

c Total weight without oil [Kg.]

d Thickness of radiator tube [mm]

e Types of mounting

43

f Vacuum withstand capability

g Total radiating surface in sq.m

h Type and make of material used for the radiators

i Total number of radiators for Transformer and dimensions of tubes

j Thickness of hot dip galvanization of radiators

37 GAS AND OIL OPERATED RELAY

a Make

b Type

c Size

d Whether supervisory alarm and trip contacts provided and their sizes and Nos

38 TEMPERATURE INDICATORS Oil Temp Indicator

Winding Temp Indicator

a Make and type

b Permissible setting ranges for alarm and trip

c Number of contacts

d Current rating of each contact

e Whether supervisory alarm contacts provided?

f Size [lxbxd]

g Nos.

h Ratio and type of CT used for winding temperature indicators.

39 APPROXIMATE OVERALL DIMENSIONS OF TRANSFORMER INCLUDING COOLING SYSTEM, TAP CHANGING GEAR ETC.

Length [mm]

Breadth [mm]

Height [mm]

40

a Minimum clearance height for lifting core and winding from tank [mm]

b Minimum clearance height for lifting tank cover [mm]

41 SHIPPING DETAILS

a Approximate weight of heaviest package [Kg.]

b Approximate dimensions of largest Package [Kg.]

42 Transformers will be transported with oil/gas.

43 MARSHALLING KIOSK

a Make and type

b Details of apparatus proposed to be housed in the kiosk

44 Details of anti-earthquake device provided, if any

45 Separate conservator and Buchholz relay provided

46 TAP CHANGING EQUIPMENT [These details refer to the basic rating of O.L. T.C. as guaranteed by OLTC manufacturers]

a Make

44

b Type

c Power flow [Uni.-directional/bi - directional/restricted bi-directional]

d Rated voltage to earth [KV]

e Rated current [Amps.]

f Step voltage [volts]

g Number of steps

h Control - manual/local- electrical/remoteelectrical

i Voltage control [Automatic/Non -automatic]

j Line drop compensation provided/not provided

k Parallel operation

l Protective devices

m Auxiliary supply details

n Time for complete tap change [one step][Sec.]

o Diverter selector switch transient time [cycles]

p Value of maximum short circuit current [Amps]

q Maximum impulse withstand test voltage with 1.2/50 micro seconds full wave between switch assembly and ground [KVP]

r Maximum power frequency test voltage between switch assembly and earth [KV-rms]

s Maximum impulse withstand test voltage with 1.2/50 micro-seconds across the tapping range [KVP]

t Approximate overall dimensions of tap changer [WxBxD] in mm

u Approximate overall weight [Kg.]

v Approximate mass of oil [Kg.]

w Particulars of the OLTC control panel for installation in control room

47 DRIVING MECHANISM BOX

a Make and type

b Details of apparatus proposed to be housed in the box

48 Types of terminal connectors and drawing No

a HV

b LV

49 Details of painting, galvanization conforms to this Specification [Yes/No]

50 Type of oil level indicator and whether Supervisory alarm contact for low oil level provided [Yes/No]

51 Type and size of thermostat to be used

52 No. of breathers provided [Nos.]

53 Type of dehydrating agent used for breathers

54 Valve sizes and numbers

a Drain valves- mm-Nos

b Filter valves- mm-Nos

c Sampling valves- mm-Nos

d Radiator valves- mm-Nos

45

e Other valves- mm-Nos

55 a Type and make of PRV

b No. of each type of devices per transformer

c Min. pressure at which device operates

56 Please enclose the list of accessories and fittings, being provided on transformer. Please confirm, these are as stipulated in the tender

57 Whether the transformer, covered is fully type tested and if so, whether copies of type test certificates, enclosed with the tender

58 Please confirm that you will guarantee maximum Impedance variation between phases within the limit of 2% only